Carotenoids are C40 isoprenoid compounds having antioxidant activity, such as astaxanthin (exists in salmons and sea lobsters), lycopene (red pigment of tomatoes), and fucoxanthin (yellowish brown or brown pigment of seaweeds). The carotenoids act as precursors of vitamin A in the body and are known to have excellent antioxidant effect, harmful oxygen scavenging action, cancer cell proliferation inhibitory action, and carcinostatic action, so as to prevent circulatory diseases, cancers, adult diseases, and the like. Beta-carotene acts as a precursor of vitamin A in the body and is known to have strong antioxidant effect, harmful oxygen scavenging action, cancer cell proliferation inhibitory action, and carcinostatic action, thereby preventing circulatory diseases, cancers, adult diseases, and the like. Recently, carotenoids have begun to become popular cosmetic ingredients in Europe and the United States, as it has been exhibited that carotenoids directly enhance the body's immune function by ultraviolet rays so as to reduce skin damage from exposure to ultraviolet rays or to inhibit melanin production. Currently, carotenoids are used as health food ingredients (nutritional supplements), pharmaceutical preparations for human, food coloring agents, animal feed pigments, or the like.
The carotenoid biosynthetic pathway is derived from famesyl pyrophosphate (FPP), an important intermediate product of the general isoprenoid pathway. FPP and isopentenyl pyrophosphate (IPP) are converted to lycopene through a series of reactions by geranylgeranyl pyrophosphate synthase encoded by CrtB, phytoene synthase encoded by CrtE, and phytoene desaturase encoded by CrtI, and then converted to beta-carotene through a series of reactions by lycopene cyclase encoded by CrtY.
Accordingly, the present inventors have made efforts to develop a novel method for increasing the production of carotenoids. As a result, the inventors have produced a recombinant vector including a gene derived from Pantoea agglomerans. The wild microorganisms which do not produce carotenoids are transformed with the recombinant vector, and then a recombinant mutant strain is produced by irradiation. As a result, the recombinant mutant strain is confirmed to have an ability to over-produce carotenoids, thereby completing the present invention.